Oxymorphone is usually made by O-demethylation of oxycodone with a variety of O-demethylation reagents such as BBr3, MeSO3H/methionine and HBr. The yield for this O-demethylation reaction ranges from 30% to 80% depending on the particular process conditions used. A low yield may result as a consequence of the strong acids or Lewis acids reacting with the functional groups of, for example, oxycodone and the product oxymorphone. Thus, use of these reagents leads to unavoidable reductions in the yield of oxymorphone due to formation of side products.